On 6/13/07, Bill Page <[EMAIL PROTECTED]> wrote:
It turns out that Axiom's list data type is very slow and almost
all the time is spent building the list. You can avoid this by
preallocating an arrary of sufficient size. E.g.
(2) -> for i in 1..20000 repeat rlist(i-1):=1.0/i
Type: Void
Time: 1.27 (EV) + 0.42 (GC) = 1.68 sec
(3) -> reduce(+,rlist)
(3) 10.4807282172 29327571
Type: Float
Time: 0.10 (EV) = 0.10 sec
(Times shown are from a 500 MHz P3 running Windows XP
and axiom-0.1.4.)
Here is another probably less obvious solution:
(1) -> reduce(+,map(x+->1.0/x,expand(1..20000)))
(1) 10.4807282172 29327571
Type: Float
Time: 0.73 (EV) + 0.02 (OT) + 0.12 (GC) = 0.87 sec
The reason that this is very fast is that 'expand' creates the
list "in situ" and the loop is internal to the 'map' operator.
See the discussion about 'expand' in
http://wiki.axiom-developer.org/SandBoxFloatSegment
Regards,
Bill Page.
_______________________________________________
Axiom-mail mailing list
[email protected]
http://lists.nongnu.org/mailman/listinfo/axiom-mail
